Researchers reporting in Current Biology on April 19 show that male fruit flies find sex—and more specifically ejaculation (xuất tinh)—to be an inherently (vốn đã) rewarding (bổ ích, thỏa mãn; đáng xem, đáng làm) experience. The study is the first to show that the rewarding nature of ejaculation is conserved among animals, from flies and mammals (động vật có vú). It also adds to evidence that manipulating sexual experience in flies affects their interest in consuming alcohol, the researchers say.

"Successful mating is naturally rewarding to male flies and increases the levels of a small peptide in the brain called Neuropeptide F," says Galit Shohat-Ophir of Bar-Ilan University in Israel. "Male flies that are sexually deprived have increased motivation to consume alcohol as an alternative reward."

* a technique in neuroscience in which genes for light-sensitive proteins are introduced into specific types of brain cells in order to monitor and control their activity precisely using light signals.